Nonfunctional adrenal tumours raise diabetes risk
medwireNews: Individuals with nonfunctional adrenal tumours (NFATs) have a nearly twofold increased risk of incident diabetes relative to those without adrenal tumours, shows research published in the Annals of Internal Medicine.
These findings call into question the use of the term nonfunctional for benign adrenal tumours discovered on abdominal imaging, say the study authors. They describe the term as potentially “inadequate and misleading” as it may not satisfactorily reflect the “the continuum of hormone secretion and metabolic risk they may harbour”.
This chart review evaluating the association between NFATs and various cardiometabolic outcomes included 166 participants with a benign NFAT and 740 without an adrenal tumour who were followed up for a minimum of 3 years. Of these, 110 and 615 individuals, respectively, did not have prediabetes or Type 2 diabetes at baseline and were therefore evaluable for the “composite diabetes” outcome.
During an average of 7.7 years, the incidence of composite diabetes was higher in participants with NFATs versus without adrenal tumours, with rates of 27.3% and 11.7%, respectively.
And individuals with NFATs had a significantly increased risk of composite diabetes relative to their adrenal tumour-free counterparts. The absolute increase in risk was 15.6% and the risk ratio, after adjusting for parameters such as age, gender, clinically relevant cardiometabolic diagnoses and medications, was 1.87.
As the study protocol specified the exclusion of individuals with potential subclinical or overt hypercortisolism, all participants had so-called normal serum cortisol levels, defined as no higher than 50 nmol/L on the 1 mg dexamethasone suppression test, explain Anand Vaidya (Brigham and Women's Hospital, Boston, Massachusetts, USA) and colleagues.
But even within the normal range of serum cortisol concentration, the prevalence of Type 2 diabetes was higher for those with higher cortisol levels, they add.
Although the small number of incident cases precludes firm conclusions, Vaidya et al believe that “a potential mechanism underlying this increased risk for diabetes may be glucocorticoid excess within a range that is considered normal by accepted standards”.
“In this regard, our findings suggest that NFATs may not be nonfunctional after all; rather, they may secrete small and inappropriate amounts of glucocorticoids that increase the risk for metabolic disease over time.”
The researchers did not find a significant link with any other included cardiometabolic outcomes (eg, hypertension, chronic kidney disease, cardiovascular events), but they conclude that “more frequent surveillance for glucose intolerance” may be warranted for individuals with NFATs.
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